Camming devices

ABSTRACT

A camming device ( 10 ) comprises a stem ( 12 ), a spindle ( 16 ) mounted on the stem, at least two cam members ( 24,26 ) adapted to engage the walls of a crack or hole by their cam profiles pivotally mounted on the spindle and adapted for opposite pivotal movement from a closed position to an open position, means ( 28,30 ) to apply a force to each cam member to urge it to its open position, and means for pivoting the cams to the closed position, characterised in that the stem is mounted directly to the spindle.

DESCRIPTION

[0001] This invention relates to camming devices, especially of the type used in climbing applications.

[0002] Camming devices, such as those known as ‘Friends’, are used to make a secure location for ropes for rock climbing. These devices are securable in cracks and the like in rock faces. A camming device generally comprises a stem carrying a transverse spindle on which are two or more, usually three or four cams that are oppositely urged to a widest extent. The cams are connected by wires to a trigger slidably mounted on the stem for retracting the cams to a narrower extent. The known camming devices fall into three main categories, namely those that have a hooped stem and a single spindle, those that have a single stem and a single spindle and those that have a single stem and twin spindles. To use such devices, the cams are retracted, so that the cams can be pushed into a crack in a rock face and then released to grip the sides of the crack. The shaping of the cams is such that the more force is applied to pull the device out of the crack increases their grip.

[0003] The stem of a camming device may be rigid or flexible. The latter may be made of wire cable and the stem is fixed in a termination mounted on the spindle. In order to hold the stem securely, the termination has to be of a reasonable length. However, undesirable leverage over rock edges on conventional terminations can damage the termination and prize the cams out of contact with the rock.

[0004] Another problem with wire cable stemmed camming devices is that when a high load has to be applied to enable full closure of the cams, the stem can buckle or fold over during use of the trigger, rendering the device difficult to place. That is especially the case with very small devices, where the cable stem is of small diameter and therefore naturally quite flexible.

[0005] An object of this invention is to provide improved camming devices.

[0006] According to a first aspect of the invention a camming device comprises a stem, a spindle mounted on the stem, at least two cam members adapted to engage the walls of a crack or hole by their cam profiles pivotally mounted on the spindle and adapted for opposite pivotal movement from a closed position to an open position, means to apply a force to each cam member to urge it to its open position, and means for pivoting the cams to the closed position, characterised in that the stem is mounted directly to the spindle.

[0007] Preferably the spindle extends either side of a location for one end of the stem. The location for the stem end is preferably a through bore in a block. In order to retain the end of the stem in the bore, the bore is preferably stepped and a ferrule or sleeve is fixed on the end of the stem to sit on the step of the bore when the stem is fed through the bore. Alternatively, the bore may narrow in diameter, so that as the stem end bearing the ferrule or sleeve is pulled through the bore, it is held tighter,

[0008] The block need not be much deeper than the spindle ends themselves, so that the stem end is only supported for a short distance and is not necessarily subject to high flexural loadings or stress. The block may have its outer edge, where the stem emerges, radiussed in order to reduce further the possibility of adverse high flexural loadings or stress.

[0009] Alternatively, the end of the stem may be fixed directly to the spindle by means of a welded or soldered joint.

[0010] According to a second aspect of this invention there is provided a camming device comprising a stem, a spindle mounted on the stem, at least two cam members adapted to engage the walls of a crack or hole by their cam profiles pivotally mounted on the spindle and adapted for opposite pivotal movement from a closed position to an open position, means to apply a force to each cam member to urge it to its open position comprising a trigger and wires linking the trigger and each cam, and means for pivoting the cams to the closed position, characterised in that the wires pass through guides mounted on the stem.

[0011] Camming devices according to the second aspect of the invention may have a single stem or may have a looped or U-shaped stem. Camming devices of the second aspect of the invention may also be camming devices of the first aspect of the invention.

[0012] One or more guides for the wires may be provided along the stem of a camming device. Guides may have a through hole for each wire or possibly a hole for each pair of wires.

[0013] The guides are preferably located axially on the stem by means of segments of coiled spring, which allow the guides to return to a preferred position during and after use. One or more spring segments may comprise an open pitch construction, which will allow the stem assembly to spring back to a normal, preferred, straight alignment.

[0014] Alternatively, the segments may be formed form one continuous piece with the guides located around its diameter and along its length by any suitable means, such as by mechanical attachment.

[0015] Another preferred alternative for the second aspect of the invention is to form the guides as larger coils between smaller coils of a coiled spring about the stem of the camming device.

[0016] Trigger wires for camming devices of the invention and generally are formed in two parts, namely a first rigid part connected to a cam and a second flexible part connected to the trigger, the two parts being jointed usually by means of a swaged collar. The two parts are overlapped and so do not share a common axis and the collar can be bulky especially relative to small cams.

[0017] According to a third aspect of the invention, therefore, camming devices generally including those according to the first and second aspects of the present invention for the rigid wire part to be formed or provided with a means for joining the second part thereto along a common axis. In one preferred embodiment, the rigid wire is formed with coils at one end having an axis common with a straight part of the wire and for one end of the flexible wire part to be insertable into those coils to share that common axis. Alternatively, one end of the rigid wire part may be formed as a tube to receive one end of the flexible wire part again to share a common axis

[0018] This invention will now be further described, by way of example only, with reference to the accompanying drawings, in which:

[0019]FIG. 1 shows a first camming device of the invention;

[0020]FIG. 2 is an exploded view of the spindle and stem of the camming device of FIG. 1;

[0021]FIG. 3 shows the assembled spindle and stem arrangement of FIG. 2;

[0022]FIG. 4 is a cut away view of the assembled spindle and stem arrangement of FIG. 2;

[0023]FIGS. 5 and 6 are respectively side views of the camming device of FIG. 1 closed and open;

[0024]FIGS. 7 and 8 are respectively perspective and side views of the camming device of FIG. 1 inserted into a crack in a rock face with the stem bent transversely to the spindle;

[0025]FIG. 9 shows the camming device of FIG. 1 in a rock face crack with the stem bent in the plane of the spindle;

[0026]FIG. 10 shows a second camming device of the invention;

[0027]FIG. 11 shows a trigger wire arrangement according to the invention for camming devices.

[0028] Referring to FIG. 1 of the accompanying drawings, a camming device for use in climbing applications comprises a flexible stem 12 fixed at one end into a block 14 from either side of which extend spindle components 16. The stem will usually be made from, wire cable and does not normally flex unless fall loads are applied.

[0029] The block 14 has a through bore 18 transversely of the spindle and the bore is stepped (20) near its bottom end. The stem 12 has a sleeve 22 crimped or otherwise secured on its free end that fits the bore 18, so that the stem can be secured in the block by passing the stem through the block, fixing on the sleeve and then pulling the sleeved end of the stem back into the block to sit on the step 20 (see FIGS. 2, 3 and 4 of the drawings).

[0030] Pivotally mounted on the spindle 16 are two pairs of inner and outer oppositely oriented cams 24,26. The cams 24,26 are biased towards an open position, i.e. to their greatest extent, by springs (not shown) between each pair of adjacent inner and outer cams 24,26. The cams are also connected by wires 28 to a trigger 30 slidably mounted on the stem 12, in order to enable the cams to be drawn to a closed position by pulling on the trigger 30. The trigger wires 28 have a first rigid part 54 connected to a cam and a second flexible part 56 connected to the trigger, the two parts being jointed by a swaged aluminium collar 58.

[0031] In the closed position the cams 24,26 cover a lesser extent than in the open position, whereby the camming device can be inserted into a crack, hole or fissure in a rock face. Then, upon release of the lever, the cams return to their open position to grip the sides of the crack or the like. The shapes of the cams means that as force is applied to pull the camming device out of the crack, the gripping force is increased. The free end of the stem has a loop 34 for attachment of ropes or other equipment.

[0032] The wires 28 pass through a pair of guides 36 on the stem 12. The guides 36 are oval in shape and have holes 38 on opposite sides of the stem, each taking the wires for a pair of cams 24 or 26. The guides are separated from each other and from the block 14 and the trigger respectively by coiled spring segments 40,42, and 44. Segment 44 continues as an open pitch spring to the end of the stem and the trigger is able to slide freely over the spring segments. The trigger is returned to its rest position by the action of the cam springs. By fixing the stem into a block between the spindle components means that a long termination can be avoided and the stem can flex closer to the cams than hitherto. Close proximity of the stem cable to the cams maintains correct loading of the spindle, so as not to prize the cams out of contact with the rock face. Undesirable leverage over rock edges on conventional long terminations can damage the termination and prize the cams out of contact with the rock. FIGS. 7 and 8 and FIG. 9 of the accompanying drawings show how the stem can bend in different directions without adversely affecting the grip of the cams. Additionally, as the spindle and block can be manufactured in one piece, there can be manufacturing benefits in terms of cost and time savings.

[0033] The provision of the guides for the wires for operating the cams allows the wires to slide freely through the guides whilst maintaining desired parallel axes of the wires and the stem. That prevents the stem from buckling relative to the wires when the trigger is operated, so that full closure of the cams can be achieved when a high level of force is applied to the trigger.

[0034] The trigger wires also slide freely through the guides when the stem is flexed over a rock edge, during which freedom of movement is necessary to avoid trigger wires prematurely levering the cams back out of position.

[0035] The provision of the separating segments of coiled spring allow the guides to return to a preferred rest position during and after use. The guides are free to move axially and rotationally on the stem and so have an inherent durability when placed over sharp rock edges.

[0036]FIG. 10 of the accompanying drawings shows another camming device 100 of the invention that has, instead of a single stem, a stem in the form of a cable wire loop 102. The ends of the loop are pivotally attached by terminations 104 to opposite ends of spindle 106, on which three cams 108,109 and 110 are rotatably mounted. Outer cams 108 and 110 face in one direction and the centre cam 109 in the opposite direction. Each cam is connected by wires 112 to a trigger bar 114 slidably mounted on the stem 102. Each limb of the stem has a guide block 116 thereon and two wires, one from an outer cam and one of the wires from the centre cam pass through each guide block. Coiled spring segments 120 and 122 are provided on each limb of the stem between the terminations and the guide blocks and the guide blocks and the trigger bar respectively.

[0037] The camming device 100 operates in a similar fashion to the camming device 10.

[0038] As can be seen in both the embodiments of FIGS. 1 and 10, the wires for operating the cams are in two parts. The first part connected to the cams themselves is a rigid wire and the second part connected to the trigger is a flexible cable, the two wire parts being joined by a swaged aluminium collar. This jointing method is relatively bulky and does not maintain a common axis for both wires as they are overlapped side by side prior to swaging. Loss of a common axis and bulky swaged joints are particularly problematic for camming devices with small cams. The combined thickness of the two joints per cam can be thicker than the cams, which limits the ability to insert the device into a rock feature. It also hinders the camming action, since the swaged joints collide with each other during triggering.

[0039]FIG. 11 of the drawings illustrates one way of reducing the size of joints between the two wire parts that may be used in any camming device, including those of the types illustrated in FIGS. 1 and 10 of the present drawings. The rigid wire component 200 connected to cam 201 is formed with several coils 202 at one end that share a common axis with the straight part 204 thereof. One end of the flexible trigger wire part 206 can be inserted into the coils 202. This forms a temporary joint during assembly that can be completed by, for example, soldering. The two parts of the trigger wire can, therefore, share a common axis and there is no need for an additional swaged alloy collar.

[0040] As an alternative to coils 202, it is possible to form the rigid wire part with a tubular section at one end to receive an end of the flexible wire part. 

1. A camming device comprising a stem, a spindle mounted on the stem, at least two cam members adapted to engage the walls of a crack or hole by their cam profiles pivotally mounted on the spindle and adapted for opposite pivotal movement from a closed position to an open position, means to apply a force to each cam member to urge it to its open position, and means for pivoting the cams to the closed position, characterised in that the stem is mounted directly to the spindle.
 2. A camming device as claimed in claim 1, wherein the spindle extends either side of a location for one end of the stem.
 3. A camming device as claimed in claim 2, wherein the location for the stem end is preferably a through bore in a block.
 4. A camming device as claimed in claim 3, wherein the bore is stepped and a sleeve is fixed on the end of the stem to sit on the step of the bore when the stem is fed through the bore.
 5. A camming device as claimed in claim 3, wherein the bore is narrower in diameter than the sleeve, so that as the stem end bearing the sleeve is pulled through the bore, it is held tighter.
 6. A camming device as claimed in claim 3, wherein the block has an outer edge and its outer edge, where the stem emerges, is radiussed.
 7. A camming device as claimed in claim 1, wherein the end of the stem is fixed directly to the spindle by means of one of a welded and a soldered joint.
 8. A camming device comprising a stem, a spindle mounted on the stem, at least two cam members adapted to engage the walls of a crack or hole by their cam profiles pivotally mounted on the spindle and adapted for opposite pivotal movement from a closed position to an open position, means to apply a force to each cam member to urge it to its open position comprising a trigger and wires linking the trigger and each cam, and means for pivoting the cams to the closed position, characterised in that the wires pass through guides mounted on the stem.
 9. A camming device as claimed in claim 8, having one of a single stem, a looped and a U-shaped stem.
 10. A camming device as claimed in claim 8, wherein at least one guide for the wires is provided along the stem of the camming device.
 11. A camming device as claimed in claim 8, wherein guides have a through hole for each wire
 12. A camming device as claimed in claim 8, wherein guides have a hole for each pair of wires.
 13. A camming device as claimed in claim 8, wherein the guides are located axially on the stem by means of segments of coiled spring, which allow the guides to return to a preferred position during and after use.
 14. A camming device as claimed in claim 13, wherein one or more spring segments comprise an open pitch construction, which will allow the stem assembly to spring back to a normal alignment.
 15. A camming device as claimed in claim 13, wherein the spring segments are formed form one continuous piece with the guides located around its diameter and along its length.
 16. A camming device as claimed in claim 8, wherein the guides are formed as larger coils between smaller coils of a coiled spring about the stem of the camming device.
 17. A camming device as claimed in claim 8, wherein the stem is mounted directly to the spindle.
 18. A camming device as claimed in claim 8, wherein the spindle extends either side of a location for one end of the stem.
 19. A camming device as claimed in claim 18, wherein the location for the stem end is a through bore in a block.
 20. A camming device as claimed in claim 19, wherein the bore is stepped and a ferrule or sleeve is fixed on the end of the stem to sit on the step of the bore when the stem is fed through the bore.
 21. A camming device as claimed in claim 19, wherein the bore is narrower in diameter than the ferrule, so that as the stem end bearing the ferrule or sleeve is pulled through the bore, it is held tighter.
 22. A camming device as claimed claim 19, wherein the block has an outer edge, where the stem emerges, which is radiussed.
 23. A camming device as claimed in claim 8, wherein the end of the stem is fixed directly to the spindle by means of a welded or soldered joint.
 24. A camming device as claimed in claim 1, wherein the means to apply a force to each cam includes a trigger and a trigger wire connecting the cam to the trigger, the trigger wire being formed in two parts, a first rigid part being connected to the cam and a second flexible part connected to the trigger, the rigid wire part being formed or provided with a means for joining the second part thereto along a common axis.
 25. A camming device as claimed in claim 24, wherein the rigid wire is formed with coils at one end having an axis common with a straight part of the wire and for one end of the flexible wire part to be insertable into those coils to share that common axis.
 26. A camming device as claimed in claim 24, wherein one end of the rigid wire part is formed as a tube to receive one end of the flexible wire part to share a common axis. 